Vicia is a genus of ca. 160 species. Most are native to the northern hemisphere but some extend further south. The Mediterranean area and western Asia (Middle East) apparently harbour most species and seem to be its center of diversity. Several species are native in Belgium too but residence status of some is uncertain (some might be rather archaeophytes): Vicia cracca L., V. hirsuta (L.) S.F. Gray, V. lathyroides L., V. sativa L. (s.l.), V. sepium L. and V. tetrasperma (L.) Schreb. (s.l.) are at least locally native in Belgium (Lambinon & Verloove 2012). Residence status of V. tenuifolia Roth is uncertain. Since its discovery in the 19th century (in very few places) its status has always been controversial (see also Durand 1899, Lawalrée 1963, Lambinon & Verloove 2012). Moreover, at least some of its stable populations recently turned out to belong to the similar but definitely non-native Vicia dalmatica (Verloove, in prep.). However, it also occurs in natural habitats relatively close to native populations in northeastern France; therefore it is here tentatively accepted as (possibly) native. Vicia orobus DC. has only recently been recorded as a presumably native species in Belgium (Schumacker & Duvigneaud 1974).
Several species of Vicia are economically important, especially as fodder crops or for green manure. Rather few are cultivated as ornamentals (Hibberd 1995, Jäger & al. 2008), possibly because they readily become weedy. Surely as a result of this weediness numerous species now occur far beyond their original distribution range.
The genus Vicia is often difficult in terms of taxonomy. Some species groups are notoriously complex and their treatments in various floras often differ much (for instance the Vicia sativa-complex or the V. cracca-complex). Moreover, intermediate plants are often encountered (see also Hosseinzadeh & al. 2008). Some characters are difficult to assess for the non-experienced botanist. In this account two important characters are used for the major subdivisions. The presence or absence of tendrils on the upper leaves is usually readily visible: these are either completely absent (rachis ending in a short mucro or rarely in a leaflet) or poorly to (mostly) well-developed. In native Vicia lathyroides tendrils are weak and simple (even non-functional) but definitely present in, at least, the upper leaves. A second important feature is provided by the inflorescence: inflorescences with a well-developed peduncle versus sessile or shortly peduncled inflorescences. The peduncle is measured from its base to the first pedicel. In case the distance is shorter than the length of a corolla, inflorescences are said to be shortly peduncled or sessile. In the other case they are long-peduncled. In the species treated herein this character is only variable in Vicia bithynica. Many other features (presence or absence of nectaries on the stipules, form and dissection of the stipules, etc.) are exceedingly variable and less reliable to divide large groups.
Some native species are very variable and at least some of this variation possibly refers to non-native infraspecific taxa. This is particularly the case in the Vicia sativa group. Vicia cassubica L. is possibly overlooked (see for instance Scheerer & Köngeter 1996, Ko & Weingart 1996, Feder 2009, Sell & Murrell 2009). It much looks like Vicia cracca but has wider pods (6-8 mm wide) with fewer seeds (1-3) and its lower calyx tooth are much shorter than the tube. It should be looked for in Belgium.
1 Leaves without tendrils, rachis usually ending in a short mucro (rarely in a leaflet) === 2
At least the upper leaves with tendrils, these short and simple or well-developed and branched === 4
2 Inflorescence nearly sessile (peduncle 3-15 mm long). Leaves with 1-3 pair of leaflets. Leaflets 10-35 mm wide === Vicia faba
Inflorescence distinctly pedunculate (peduncle 20-90 mm long). Leaves with 9-16 pair of leaflets. Leaflets 1-8 mm wide === 3
3 Annual. Pod sessile, torulose. Inflorescence 1-4-flowered. Calyx teeth subequal, all as long as or longer than calyx tube === V. ervilia
Perennial. Pod pedicellate, not torulose. Inflorescence 6-24-flowered. Calyx teeth unequal, all shorter than calyx tube (native) === V. orobus
4 Inflorescence sessile or shortly-peduncled, in the latter case peduncle shorter than a corolla. Flowers usually 1-7 === 5
Inflorescence distinctly pedunculate, peduncle much longer than a corolla === 20
5 Standard hairy on the back === V. pannonica
Standard glabrous throughout === 6
6 Calyx mouth not oblique, calyx teeth subequal === 7
Calyx mouth oblique, calyx teeth unequal === 12
7 Standard yellow or cream === 8
Standard purplish === 9
8 Corolla pure yellow (wings sometimes blackish at tip), 23-35 mm long, chasmogamous === V. grandiflora
Corolla cream, 15-20 mm long, often cleistogamous === V. sativa s.l. p.p.
9 Seeds tuberculate. Tendrils simple. Corolla up to 14 mm long. Pod 15-40 x 3-5 mm === 10
Seeds smooth. Tendrils branched. Corolla 14-30 mm long. Pod 25-70 x 3-11 mm === 11
10 Corolla 6-9 mm long, purple. Pod 15-30 x 3-4 mm, with short beak. Leaves with up to 4 leaflet pairs, leaflets of upper leaves merely mucronate at apex (native) === V. lathyroides
Corolla 10-14 mm long, usually paler. Pod 30-40 x 4-5 mm, with long beak. Leaves with up to 6 leaflet pairs, leaflets of upper leaves long acuminate at apex === V. cuspidata
11 Leaves with 1-3 pair of leaflets. Stipules large (10-15 x 3-9 mm), without a nectary on the abaxial side === V. bithynica p.p.
Leaves usually with at least 4 pair of leaflets. Stipules smaller (3-5(-10) x 1-3(-6) mm), always with a distinct nectary on the abaxial side === V. sativa s.l. p.p.
12 Leaves with 1-3 pair of leaflets. Leaflets up to 50 mm long and 35 mm wide === 13
Leaves usually with at least 4 pair of leaflets, these much shorter and narrower === 14
13 All leaflets entire (or the upper ones rarely with some small teeth in the upper half). Stem robust, erect. Flowers usually 1-2(-3) === V. narbonensis
At least the upper leaflets coarsely serrate throughout. Stem more flaccid, much branched. Flowers usually 2-4(-6) === V. serratifolia
14 Perennial. Corolla purplish. Inflorescence 2-6-flowered (native) === V. sepium
Annual. Corolla yellowish or cream (rarely whitish pink). Inflorescence 1-4-flowered === 15
15 Valves of young pod pubescent (often glabrescent with age). Inflorescence sessile, 1(-2)-flowered === V. lutea
Valves of young pod glabrous (but sometimes ciliate along margins). Inflorescence shortly peduncled, 1-4-flowered === 16
16 Margin of pod tubercled-ciliate === 17
Margin of pod smooth === 18
17 Wings of corolla entirely greenish yellow or with a weak brownish spot at apex, ca. 15 mm long === V. loiseaui
Wings of corolla greenish yellow with a distinct blackish spot at apex, ca. 22 mm long === V. melanops
18 Tendrils short, usually simple. Leaflets 5-18(-20) mm long, 1-3 mm wide. Pod 15-18 (-22) x 6-8 mm === V. assyriaca
Tendrils longer, usually branched. At least some leaflets longer than 20 mm and wider than 3 mm. Pod 20-40 x 8-12 mm === 19
19 Inflorescence 1-2-flowered. Corolla yellowish. Limb of standard slightly shorter than claw === V. hyrcanica
Inflorescence (1-) 2-5-flowered. Corolla cream to whitish pink. Limb of standard equal to or slightly longer than claw === V. noeana
20 Corolla 2-9 mm long and inflorescence 1-8-flowered (native) === V. hirsuta and V. tetrasperma s.l.
Corolla longer or inflorescence with more flowers === 21
21 Leaves with 1-3 pair of leaflets. Inflorescence 1-3-flowered === V. bithynica p.p.
Leaves usually with at least 4 pair of leaflets === 22
22 Upper leaflets ovate. Stipules deeply dentate. Perennial === V. dumetorum
Upper leaflets lanceolate-linear. Stipules entire or dentate. Annual or perennial === 23
23 Inflorescence 1-2-flowered. Stipules bipartite, with entire lobes === V. monantha
Inflorescence always with more flowers. Stipules entire or dentate === 24
24 Corolla with limb of standard at least as long as claw === 25
Corolla with limb of standard shorter than claw === 27
25 Corolla ca. 8-12 mm long. Limb of standard about as long as claw (native) === V. cracca
Corolla ca. 12-18 mm long. Limb of standard longer than claw === 26
26 All leaflets linear-setaceous, 1-2 mm wide. Inflorescence lax, 8-20-flowered === V. dalmatica
At least lower leaflets linear-lanceolate, 2-6 mm wide. Inflorescence dense, 15-30-flowered (native) === V. tenuifolia
27 Corolla reddish-purple, blackish at tip. Valves of young pod pubescent === V. benghalensis
Corolla violet or purplish, without blackish tip. Valves of young pods often glabrous, more rarely pubescent === V. villosa s.l.
Additional aliens: Vicia hybrida L. (Medit., W-As., grain alien), V. peregrina L. (S-Eur., wool and grain alien), V. sicula (Rafin.) Guss. (Italy, Sicilia, grain alien?), V. sylvatica L. (N, C and E-Eur., W and C-As., vector unknown) and V. villosa subsp. eriocarpa (Hausskn.) P.W. Ball (syn.: V. eriocarpa (Hausskn.) Hal., V. varia var. eriocarpa Hausskn.) (C-Medit., grain alien?).
Vicia olbiensis Reuter was reported as an alien from Belgium by Lawalrée (1963) but this is only a robust form of V. lathyroides and now merely included in the synonymy of the latter (Euro+Med Plantbase).
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